Electric devices and electronic devices are required to provide electromagnetic non-interference and tolerance (Electromagnetic Compatibility (EMC)). For example, when an electrostatic voltage is applied to a metal portion, such as a connector, exposed to a surface of an electronic device, noise due to the voltage propagates through the metal portion of the device and enters a printed circuit board to cause an erroneous operation. CISPR 24, which is an international standard for information devices, requires that the devices should operate normally when a voltage of 4 kV is applied through contact discharge and a voltage of 8 kV is applied through aerial discharge in an Electrostatic Discharge (ESD) test.
For the electromagnetic tolerance, for example, there is provided a technology for checking ESD tolerance by specifying a location of application of static electricity and comparing the distance from the specified location to a printed circuit board and the distance from the specified location to a metal structure provided to conduct the static electricity to the earth.
For the electromagnetic non-interference, there are provided technologies for checking Electromagnetic Interference (EMI). For example, in one technology, information on wiring of a printed circuit board is referenced to check whether a guard ground, which is a guard pattern of a ground attribute, is provided within a prescribed distance from a signal pattern. In another technology, it is checked whether a ground plane for preventing noise for a signal pattern and a bypass capacitor for preventing noise for a power supply are not connected to each other.
In recent years, for the electronic devices such as cellular phones and personal computers, in particular, the component mounting density has become higher, the material of housing components has been changed from a metal to a resin, and the structure of semiconductor devices has been changed along with size and weight reductions, an increase in speed, and a reduction in power consumption, and the ESD tolerance has been lowered accordingly.
Previously, the ESD tolerance was successfully improved by making modifications to the housing etc. in the device prototype stage. However, housings with a reduced size and printed circuit boards with a reduced mounting area do not allow such modifications, and it is difficult to improve the ESD tolerance in the same way as in the related art. Thus, it is preferable to take ESD measures in the printed circuit board design stage. However, there has not been provided any technology that allows specifying from design data on the printed circuit board a location that may be problematic from the viewpoint of ESD measures.